Rectangle distance and tests

packages/math/rectangle.test.ts

@@ -0,0 +1,39 @@
+import { point } from "./point";
+import { rectangle, rectangleDistanceFromPoint } from "./rectangle";
+
+describe("rectangle distance", () => {
+  it("finds the shortest distance", () => {
+    expect(
+      rectangleDistanceFromPoint(
+        rectangle(point(-1, -1), point(1, 1)),
+        point(2, 0),
+      ),
+    ).toBe(1);
+    expect(
+      rectangleDistanceFromPoint(
+        rectangle(point(-1, -1), point(1, 1)),
+        point(0, 2),
+      ),
+    ).toBe(1);
+    expect(
+      rectangleDistanceFromPoint(
+        rectangle(point(-1, -1), point(1, 1)),
+        point(-2, 0),
+      ),
+    ).toBe(1);
+    expect(
+      rectangleDistanceFromPoint(
+        rectangle(point(-1, -1), point(1, 1)),
+        point(0, -2),
+      ),
+    ).toBe(1);
+  });
+  it("finds the corner as closest point", () => {
+    expect(
+      rectangleDistanceFromPoint(
+        rectangle(point(-1, -1), point(1, 1)),
+        point(2, 2),
+      ),
+    ).toBe(Math.sqrt(2));
+  });
+});

packages/math/rectangle.ts

@@ -1,19 +1,19 @@
 import { invariant } from "../excalidraw/utils";
+import { point } from "./point";
+import { segment, segmentDistanceToPoint } from "./segment";
 import type { GenericPoint, Rectangle } from "./types";
 
 export function rectangle<P extends GenericPoint>(
-  a: P,
-  b: P,
-  c: P,
-  d: P,
+  topLeft: P,
+  bottomRight: P,
 ): Rectangle<P> {
-  return [a, b, c, d] as Rectangle<P>;
+  return [topLeft, bottomRight] as Rectangle<P>;
 }
 
-export function rectangleFromQuad<P extends GenericPoint>(
-  quad: [a: P, b: P, c: P, d: P],
+export function rectangleFromPair<P extends GenericPoint>(
+  pair: [a: P, b: P],
 ): Rectangle<P> {
-  return quad as Rectangle<P>;
+  return pair as Rectangle<P>;
 }
 
 export function rectangleFromArray<P extends GenericPoint>(
@@ -26,3 +26,17 @@ export function rectangleFromArray<P extends GenericPoint>(
 
   return pointArray as Rectangle<P>;
 }
+
+export function rectangleDistanceFromPoint<Point extends GenericPoint>(
+  r: Rectangle<Point>,
+  p: Point,
+): number {
+  const sides = [
+    segment(point(r[0][0], r[0][1]), point(r[1][0], r[0][1])),
+    segment(point(r[1][0], r[0][1]), point(r[1][0], r[1][1])),
+    segment(point(r[1][0], r[1][1]), point(r[0][0], r[1][1])),
+    segment(point(r[0][0], r[1][1]), point(r[0][0], r[0][1])),
+  ];
+
+  return Math.min(...sides.map((side) => segmentDistanceToPoint(p, side)));
+}

packages/math/segment.ts

@@ -1,4 +1,3 @@
-import { invariant } from "../excalidraw/utils";
 import {
   isPoint,
   pointCenter,
@@ -23,10 +22,9 @@ import {
  * @returns The line segment delineated by the points
  */
 export function segment<P extends GenericPoint>(a: P, b: P): Segment<P> {
-  invariant(
-    !pointsEqual(a, b),
-    "The start and end points of the segment cannot match",
-  );
+  if (pointsEqual(a, b)) {
+    console.warn("The start and end points of the segment cannot match");
+  }
 
   return [a, b] as Segment<P>;
 }

packages/math/types.ts

@@ -88,7 +88,7 @@ export type Triangle<P extends GenericPoint> = [a: P, b: P, c: P] & {
 /**
  * A rectangular shape represented by 4 points at its corners
  */
-export type Rectangle<P extends GenericPoint> = [a: P, b: P, c: P, d: P] & {
+export type Rectangle<P extends GenericPoint> = [a: P, b: P] & {
   _brand: "excalimath__rectangle";
 };